I am a digital strategist and entrepreneur who has worked with non profits, museums, Fortune 500 and start ups. My work has included 2 mobile applications on both App Store and Google Play. Invested in a technology start up and written the book Manage Your Web.
I would stay self funded as long as possible. Then move to testing the prototype with customers. If you merge the results from experts and the customers then you have a high chance to presenting to investors and share the data.
Im available to talk more and help in anyway possible.
You can start by having a text to download sign up on your website. I use Link Texting. You can also create a landing page that can build a email listing so that you can send emails to people who are interested in your app features. Read a article by Kevin Kelly called 1,000 True Fans.
I would reach out to developers on LinkedIN or post a question on Quora. Or if you have specific needs I would be willing to set up a call and talk to you about app store optimization.